question_answer

The standard enthalpy change for the reaction \[{{H}_{2}}(g)+\frac{1}{2}{{O}_{2}}(g)\xrightarrow[{}]{{}}{{H}_{2}}O(g),\]is \[\Delta {{H}^{o}}=-248.8kJ\]It truly suggests, that

A)  248.8 kJ of energy is evolved when reaction is proceeded at 1 atm pressure and 298 K temperature.

B)  248.8 kJ of energy is evolved irrespective of reaction conditions (pressure and temperature).

C)  the reaction \[2{{H}_{2}}+{{O}_{2}}\xrightarrow[{}]{{}}2{{H}_{2}}O\] evolves same amount of energy 248.8 kJ

D)  The reaction is \[{{H}_{2}}(g)+\frac{1}{2}{{O}_{2}}(g)\xrightarrow[{}]{{}}{{H}_{2}}O(l)\]